FDG-PET has an expanding role in head and neck cancer management as it provides improved staging, treatment response delineation and recurrence detection for a wide range of solid cancers [
23] including head and neck disease [
24]. It has excellent sensitivity and specificity rates (96% and 98.5%) for cervical nodal staging [
25]. In comparison to FDG-PET, the sensitivity and specificity of CT and MRI were lower in many studies, ranging from 64% [
26] to 95% [
27] and from 41% [
28] to 97% [
27], respectively. Post treatment FDG-PET is often of great value in predicting residual viable tumor [
29]. Early work from a number of groups suggests that FDG-PET/CT disease targeting can help assist conformal radiotherapy and IMRT planning in several diseases including head and neck disease [
30]. Lowe et al. investigated 44 patients with head-and-neck tumors after primary radio chemotherapy. A year after treatment, FDG-PET showed viable tumor tissue in 16 cases and histological data confirmed the diagnosis made by PET. The sensitivity was 100% for FDG-PET and 38% for CT plus MRI. The specificity of FDG-PET was 93% and of CT and MRI 85% [
31]. Kunkel et al. found a significant correlation between FDG uptake after neoadjuvant radiation treatment and histological response of mouth carcinoma [
32]. Also, Nishioka et al. showed that the integration of FDG-PET in radiation treatment planning for oropharyngeal (twelve patients) and nasopharyngeal (nine patients) carcinomas may also cause a reduction in the radiation fields. The GTV for primary tumor was not changed by image fusion in 19/21 patients (90%). Of the nine patients with nasopharyngeal cancer, the GTV was enlarged by 49% in only one patient and decreased by 45% in one patient. In 15/21 patients (71%) the tumor-free FDG-PET detection allowed normal tissue to be spared. Particularly, parotid glands were spared and, thus, xerostomia could be avoided. The authors concluded that the image fusion between FDG-PET and MRI/CT was useful for encompassing the whole tumor area in the irradiation field and for sparing of normal tissue in GTV, CTV and PTV determination [
33]. FDG-PET/CT provides more accurate assessment than CT imaging of treatment response and in high index suspicion patients, PET-CT performed within four weeks after radiotherapy treatment were highly predictive for residual disease [
34]. FDG-PET can also aid in determining response to organ preservation treatment in head and neck cancer, where true disease status after radiation is often obscured by fibrosis. Greven et a1 [
35] reviewed the utility of FDG-PET in 31 patients suspected of persistent disease after definitive radiation therapy for carcinoma of the larynx. The overall sensitivity of FDG-PET was 80% and the specificity was 81%. The authors concluded that potentially morbid post-treatment biopsy can be postponed in FDG-PET-negative patients, despite clinical evidence of persistent disease. Similarly, Farber et a1 [
36] reviewed their experience with 28 patients with head and neck cancers treated with definitive radiation therapy, all suspected of harboring recurrent/persistent disease. Twelve of 13 patients with FDG-positive scans had biopsy-proven active disease; 2 of 15 patients with negative PET imaging did have residual disease, yielding an overall accuracy of 89%. Others have also observed high sensitivity and specificity values for FDG-PET in a similar setting of suspected residual/recurrent disease after definitive treatment [
37,
38]. Thus the results of FDG-PET imaging can guide early intervention following treatment, potentially at a stage when surgical salvage is still possible.